re: Best way to process venison into burger?

When I’ve made it myself, I use (guesstimated) 10-15% brisket or 5-10% ribeye fat mixed in.

The place I have mine processed now uses 10% Wagyu trimmings and it’s terrific.

For many many years, the processors I used mixed it with pork. Fine for sausage, but now my ground tastes like beef, and to me is much better than with pork.